Want a marshmallow?  I see that Neato is a true European, he can’t throw anything.  I bet if we gave him a soccer ball he could move that!

This is a 50 minute lecture introducing the ideal gas law.  He is moving from the scale of a single molecule to Avogadro’s number of them.  This is a more traditional Chem 1 topic and will probably find more utility by many chemists.

Details

Just a bit more on MO theory, Neato ties the bow to the package.

Hybridizations go from s sp sp2 sp3 dsp3 d2sp3.  This is going from steric number 1 2 3 4 5 6 with geometries of linear, trigonal planar, tetrahedral, trigonal bipyramidal and octohedral.  And that does it.

The point of all this is that say you have a molecule like ethylene, C2H2.  What’s it’s hybridization and geometry?  You draw its LDS or count electrons and you learn that it’s linear with sp hybridization.

What about uranium hexafluoride?  Well, uranium is surrounded by 6 fluorines.  That’s octahedral geometry with d2sp3 hybridization.  That’s how this MO theory is often used.

Ideal Gas Law (IGL)

Standard temperature and pressure (STP) is 1 atm or 760 mm Hg or 760 torr or 10^5 Pa.

Let’s just go straight for the prize.  The ideal gas law is:

PV = nRT

P is pressure in atm

V is volume in Liters

n is number of moles

R is the IGL gas constant = 8.314 J/K mole

T is temperature in Kelvin (273 + temp in Celsius)

*Please note that this relationship is only valid when there is no interaction between gas molecules, when high temperatures, low pressures, low intramolecular forces prevail.*

There are alot of relationships here.  With constant temperature, if pressure rises, volume must fall.  With constant volume, if pressure rises, temperature must rise.  With constant pressure, if volume falls, temperature falls.  And so on.  Remember the equation and build some instinct.

Boyle’s Law

P1V1 = P2V2

There are other variations with the Guy-Lussac Law but we have IGL which is all you need, along with the skills to move variables about.  Please memorize IGL you will actually use it.

Review

You may now file away MO theory with QM.  It’s just another tool.  We are like carpenters which are in a store buying hammers, awls, screwdrives and such.  Some tools have more general utility.  All this education is giving you a toolbox.  Each tool has a job.

Phases of matter, from high energy to low: gas liquid solid.

Remember orbitals – s, p, d, f and their filling order  1s2 2s2 2p6 3s2…

IGL is PV = nRT.  One mole of any gas in the world at STP is 22.4 liters, about the size of a basketball.  Standard volume is 1 atmosphere, standard temperature is 25 degrees Celsius or about 300K.  n is moles and R is 8.314 J/K Mole

This is a 50 minute lecture on MO theory.

Details

Two types of MOs: bonding and antibodies.  Bonding MOs are lower in energy than antibonding MOs.  Pie MOs are lower in energy than sigma MOs.  Pie MOs come from p orbital overlap, whereas sigma MOs come from s orbital overlap.

What is the hybridization on benzene?

Well, first what is the bond angle?  Clearly it is 120 since each carbon has sp2 hybridization.  Essentially you count the number of atoms and lone pairs surrounding it.  Benzene is C6H6 and the number of surrounding is 3, so it is sp2 for the central atoms..

The more nodes, the more energy.  If you are concerned about your understanding, don’t panic!  VSERP, LDS, and MOs are among the most difficult subjects in chemistry.

Reviews

Nietzsche spends alot more time on MOs today.  In the end, it all comes down to energy.  “The molecule” does whatever it can to minimize energy, lower reactivity, and to become more stable.  It does this as a result of QM and other natural laws.  That’s the big picture.